Frequently Asked Questions › Preconditions and Environment to Run Arcserve UDP Data Store Capacity Planning Tool › What is the disk space occupied on the server running Arcserve UDP Data Store Capacity Planning Tool to save hash keys?

What is the disk space occupied on the server running Arcserve UDP Data Store Capacity Planning Tool to save hash keys?

During the node scan, Arcserve UDP Data Store Capacity Planning Tool reads all the valid source data and divides them into 4 KB/8 KB/16 KB/32 KB/64 KB blocks and generates hash keys, after which Arcserve UDP Data Store Capacity Planning Tool sends them to server in the Node Scan Data folder.

You can estimate the disk space occupied on the server running Arcserve UDP Data Store Capacity Planning Tool to save hash keys by using the following example:

Example: Consider that the valid source data size is 1 GB.

• The number of hash keys with 4 KB deduplication block size: 1 GB/4 KB = 256 KB
• The number of hash keys with 8 KB deduplication block size: 1 GB/8 KB = 128 KB
• The number of hash keys with 16 KB deduplication block size: 1 GB/16 KB = 64 KB
• The number of hash keys with 32 KB deduplication block size: 1 GB/32 KB = 32 KB
• The number of hash keys with 64 KB deduplication block size: 1 GB/64 KB = 16 KB

The size of each hash key is 16 bytes. For every hash key, when Arcserve UDP Data Store Capacity Planning Tool writes it to the hash key file, it also records its raw size/compression size with standard compression/compression size with maximum compression. This needs extra six bytes.

The size of hash key file: (256 KB + 128 KB + 64 KB + 32 KB + 16 KB) * 22 bytes = 10.66 MB

The size of hash key file depends on the valid data size on source nodes.

1 GB:10.66 MB = 96.1: 1

Every 100 GB source data needs approximately 1 GB space to store hash key files on the deduplication assessment server.

Note: If 100 GB source data is scanned twice, 2 GB space is required on the server and if scanned thrice, 3 GB space is required and so on.